Method of making color-television screens



Dec. 20, 1955 H. B. LAW

METHOD OF MAKING COLOR-TELEVISION SCREENS 2 Sheets-Sheet 1 Filed March18, 1952 Harold Dec. 20, 1955 w 2,727,828

METHOD OF MAKING COLOR-TELEVISION SCREENS Filed March 18, 1952 2Sheets-Sheet 2 Har gd fiY i iiw United States Patent 0 METHOD OF MAKINGCOLOR-TELEVISION SCREENS Harold B. Law, Princeton, N. J., assignor toRadio Corporation of America, a corporation of Delaware ApplicationMarch 18, 1952, Serial No. 277,133

7 Claims. (Cl. 117-335) This invention relates to color-kinescopes andother cathode-ray tubes of the kind employing a ray-sensitive screen ortarget of the repetitive or mosaic variety, and to improvements in theart of manufacturing such targets and tubes. Considered from one aspectthe present invention may be said to comprise an improvement upon theinvention described in the copending application of Harold B. Law,Serial No. 158,901, filed April 28, 1950; now U. S. Patent No.2,625,734, issued January 20, 1953.

The cathode-ray tubes employed in color-television transmitters andreceivers usually contain an image-screen made up, effectively, of amultiplicity of similar groups of line-like or dot-like ray-sensitiveareas of sub-elemental image dimensions. There are usually threesub-elemental areas in each group; each of said areas being allotted toone or" the primary colors (say, red, blue and green, respectively). Ifthe tube is a receiving tube (i. e. a kinescope) the preferred practiceis to cover the target surface of each of said sub-elemental screenareas with a phosphor material of the required color-responsecharacteristic. However, satisfactory results may also be achieved bythe use of a continuous coating of a black and white phosphor (e. g. P4)and a multi-color optical filter disposed on or adjacent to the obverseface of the screen. (As to this see, by way of example, Zworykin1,691,324). Similarly, if the mosaic is designed for use in acolor-camera or pickup tube, appropriate color-sensitive filters may beused in conjunction with a continuous photoemissive layer.

The ability of tubes of this general character to handle a color-imagewithout color dilution, loss of contrast, and other image-defectsdepends, in large measure, upon the achievement of the correct size andproper geometric location of the numerous sub-elemental areas of themosaic with respect to the path of scan of the electronbeam or beamswhich serve selectively to energize said screen areas.

In the simplest case, i. e. where the mosaic electrode (or image-screen)is to be used in a color tube of the so-called accurate scanning variety(see Zworykin 2,415,059, and Rudenberg 1,934,821), the principalrequirement is that the color emissive areas be distributed uniformly onthe target. As set forth on page 452 of the September 1951 edition ofRCA Review: Line or dot screens operated by this method require lines ordots which are of a size less than one-third of the distance betweenscanning lines (when scanned parallel) or less than one-third of apicture-element size (when scanned transversely). Thus, the dimensionsand pattern of distribution of the color-emissive areas on the screen ofa tube of the accurate scanning variety can readily be calculated,mathematically. The mosaic pattern, thus calculated, may be applied to asuitable foundation surface in any of a number of ways, (e. g. by meansof a stencil and spray gun, or by silk-screening or other printingprocess).

In tubes wherein the image screeh, per se, comprises but one element ofa bi-p'ai't or mum-part target assembly 2,727,328 Patented Dec. 20, 1955the exact distribution of the color-areas on the screen presents a morecomplex problem than it does in tubes of the above describedaccurate-scanning variety. Thus, if the tube is of the so-called shadowmask variety (wherein an apertured mask casts a Crookes-shadow upon allscreen areas other than the ones selected for illumination), theplotting of a truly accurate screen pattern involves a consideration notonly of the pattern of the shadows cast by the mask but also of possibleimperfections in said pattern resulting from minor inaccuracies in thedistribution and contour of the mask apertures.

Several screen-plotting methods have heretofore been devised forovercoming the above mentioned complications in the design of a mosaicscreen for use in cathoderay tubes of the shadow-mask variety. All ofthese priorart methods depend for their efiectiveness upon the fact thatin such tubes the scanning beam or beams follow straight paths intraversing the space between the mask and the screen. (This is sobecause the mask and. the screen are operated at the same potential,hence the space therebetween is a field-free region through which theelectrons travel Without being subjected to any undesired deflectingforce). Accordingly, as described by Dr. Werner Flechsig in FrenchPatent 866,065, the mask itself may be used as a stencil through whichthe different color-phosphors may be deposited upon a suitablefoundation plate. in another method, claimed by H. B. Law (in U. S.Patent No. 2,625,734), the pattern of the mask-apertures is firstphotographed by exposure to rays projected through the mask from a pointdisposed a suitable distance from the mask. The photographic pattern isthen used to make a stencil which, when mounted upon a silkscreen, isused in laying down the difierent color-phosphors (in the form of apaste) on a suitable foundation plate.

Neither the Flechsig method nor the Law method can be used in plottingthe pattern of a mosaic screen for use in a cathode-ray tube of any kindwherein the screen assembly comprises one or more lenticular fieldelectrodes or grills operated at a potential other than that applied tothe screen. The reason for this is that the application of differentpotentials to the viewing screen and grill- (or to adjacent grills)creates an electron-optical lens-field which causes the electrons tofollow curvilinear paths instead ofthe straight paths that they wouldfollow in the absence of such a held. The direction and extent or" thebeams departure from a straight line depends upon the number (single orcompound) and kind (cylindrical or spherical) of lens-fields set upWithin the screenassembly. In any event, an electron-beam when subjectedto the influence of the difierent potentials of a lenticulargrill tubewill not impinge upon the same elemental area of a mosaic-screen that itwould in a cathode-ray tube of the accurate scanning or shadow-maskvarieties. Thus, if as taught in Flechsigs French patent, thedifierently colored elements of a mosaic-screen are disposed in the samelocation in a lenticular-grill tube as they are in a shadow-mask tube,the result is an unintelligible, or at east badly distorted,color-image.

Accordingly, an object of the present invention is to provide a highlyaccurate method of and means for plotting the pattern of a mosaic screenfor use in cathoderay tubes, including those of the so-cailedlenticulargrill variety.

Another and related object of the invention is to provide improvedcolor-television tubes which shall be characterized by the purity andbrilliance of their images, by their trouble-free performance and bytheir adaptability to mass production methods.

The foregoing and other objects are achieved in accordance with theinvention by the provision of a novel electronic plotting method whereinelectrons are caused to a ri ht an les to the wires of the other grill.

approach a recording target along the same paths that they approach theimage-screen of the particular type of tube to which the invention isapplied. As will hereinafter more fully appear, the recording targetpreferably comprises an insulating foundation p ate coated on one sidewith a photographic emulsion which is sensitive to electron impact and,preferably, insensitive to stray light rays such as those which mayemanate from the cathode or cathodes of the plotting apparatus. Theemulsion covered surface of saidplate is also rendered electricallyconductive so that it may be given the same potential, or relativepotential. that the ima e-screen is to assume in the target-assembly ofthe finished tube. Thus, the electron-beam or'beams in the plottingapparatus are caused to follow the same sraightor curved paths that theelectron-beam -or beams in the finished tube will follow. As aconsequence, the pattern with which the plotting beams impinge upon theemulsion covered surface of the recording target is an exact plot of themosaic pattern required to ensure color purity and optimum performanceof the tube for which said mosaic is designed. -The invention isdescribed'in greater detail in connection with the accompanying twosheets of drawings Wherein:

Fi 1 isa side-elevational view, partlv in section. of a .so-calleddemountahle cathode-ray tube suitable for use in connection with thescreen-plotting method of the invention;

Fi 2 is a fra mentarv view in perspective. taken from the rear of the frnt secti n of the tube of Fig. 1. showing one form of lent cnlarri lassembly throu h which elecgons1 approach the recording target in theapparatus of Fig. 3 is a partlv dia ramm tic side elevat on of thetri-part tar et assembl of Fi 2. s owin how the normally s rai ht p thsof the three beams are diverted by the lens action of he two rills insaid assembly;

' Figs. 4. 5 and 6 are sect onal views showing a silk screen and acontriva ce compri in a pair of eccentric pins for p sitioning t escreen n th lass foundation plate of the tar et when applying differentcolor-phosph rs to said late.

The invention is herein described as applied to the plotting and manufcture of a line-screen for usein a threeun tri-color kin scope of thelenticular rill variety described by Edward G. Ra berg in copendin aplication" Serial N 277.182 filed concurrently herewith. However. itwill be apparent as the description proceeds that the demountable vacuumtube shown in Fi s. 1 and 2 may be used in layin out any of the variousdot-like or line-like patterns empl ved on the plane or curved screensused in color-television and stereoscopic-television image tubes. 1

In practicin the screen-plotting method of the invention the fieldelectrode or electrodes of the screen assemblv, or replicas thereof. arefirst set up in front of electron-sensitive recording tar et. such as aphoto ra hic plate, in the same relative position that said fieldelectrodes or lens elements are to occupy with respect to the screen ofthe tube for which they are desi ned.

Fig. 2 shows a target assembly wherein two field electrodes 1 and 3 aredisposed in front of the emulsion covered surf ce 5 of a ph to raphicplate 7 and the entire assembly mounted within the dernountable tube ofFi l in the position required for the plott n operat on. Here, as in theRam er discl sure. the field electrodes. compr se two wirerills 1 and 3disposed in spaced apart parallel planes with the wires of one grillextending at The spacin between the grills 1 and 3 and the spacinbetween grill 3 and the emulsion covered surface 5 of the plate 7 isestablished as by insulating pieces 9 and 11 disposed between saidparts. The entire assembly is supported on metallegs 13 which serve alsoto connect the first l grill 1, electrically, to the metal wall of the tb?- Til? wall thus serves as an accelerating electrode similar to theconductive coating on the inner wall of the main chamber of the Rambergtube.

The viewing screens used in cathode-ray tubes of the lenticular-grillvariety are electrically conductive. It is therefore essential that thephotographic plate 7, or its emulsion covered surface 5, also beconductive so that it may be maintained at the same relative potentialas the screen in the tube for which the screen is designed. Furthermorewhen, as in the instant case, the recording target comprises anelectron-sensitive photographic plate, it should preferably be one whichis substantially immune to visible light rays such, for example, asthose of the wave-lengths released as an incident to the thermionicemission of electrons from the cathode of the electron gun or guns inthe plotting apparatus. Specific formulas for such an electricallyconductive, electron-sensitive, light insensitive photographic plate areclaimed in the joint application of H. B. Law, N. Rynn and J. Evans incopending application Serial No. 277,132 filed concurrently herewith.One such formula comprises: a gelatin emulsion containing silver halidesalts impregnated with a red dye, such as basic fuchsin, and the surfacecoated with a thin (electron transparent) stratum of graphite which ispolished or. bufied to lower its electrical resistance.

The plotting apparatus of Fig. 1 comprises an evacuable main chamber 17having front and rear metal side walls 19 and 21, respectively. Thefront section 19 of the main chamber 17 terminates in a window 23 set ina demountable vacuum-tight window frame 25 upon which the targetassembly 1, 3, 5, 7,'shown in Fig. 2, is mounted. The rear part 21 ofthe main chamber 17 terminates in a demountable glass neck portion 27which is dimensioned to receive an electron gun assembly 29 in the sameposition, with respect to thetarget assembly, as in the finished tube.

The gun assembly is preferably a duplicate of the one to be used in theparticular type of tube that has been selected. for production. In theinstant case the gun-assembly comprises a battery of three guns, 29R,29B and 29G arranged delta-fashion (i. e. in a triangular pattern) aboutthe long central axis of the neck 27 in the manner claimed by Alfred C.Schroeder in copending application Serial No. 730,637 filed February 24,1947, now U. S. Patent No. 2,595,548, issued May 6, 1952. The details ofconstruction of the electron-gun assembly may be as described by HannahC. Moodey in copending application Serial No. 295,225 which is basedupon ap plication Serial No. 166,416 filed June 6, 1950, now abandoned.As in the Schroeder and Moodey disclosures, a magnetic yoke 31 on theglass neck 27, in front of the gun assembly, serves to impart a scanningmovement to the beam or beams emanating from the gun assembly 29.

The front portion 19 of the main chamber 17, and hence the targetassembly therein, may be rotated about the axis of the tube, as by meansof a pinion 33 and gear 35, for the purpose of orienting the targetassembly with respect to the path of scan of the beam electrons. Suchrotary movement is facilitated by ball bearings 37 and 39 which operatein raceways 41 and 43 on the insulating pedestals 45 and 47 uponwhichthe entire assembly is supported. A gasket 49 seated in a flange 51between the rotatable front and stationary rear sections 19 and 21 ofthe main chamber permits the entire front section 19, 23, 25 to berotated without breaking the vacuum. Asuitably high vacuum isestablished within the entire structure by a pumping system (not shown)connected to an exhaust port' 53 in the rear or stationary section 21 ofthe main chamber 17.

In both single gun and multiple-gun tri-color kinescopes of the subjectvariety the particular color area that is illuminated at any giveninstant is a function of the particular angle or direction at which thebeam electrons approach the screen. Where, as in the instant case, threeguns are employed, the beam from the gun 29R approaches the target fromthe direction required to strike the areas on the target surface 5 whichare to be allotted to the red phosphor and the other two guns 29B and29G are so positioned that their beams approach said surface 5 at theparticular angles required to strike the blue and green areasrespectively.

As previously set forth, in tubes of the lenticular grill variety thelens action of the field electrodes or grills causes the beam electronsto depart from the straight paths which they travel in approaching thefirst grill 1. This is illustrated in Fig. 3, wherein, as a result ofthe relative voltage distribution illustrated in Fig. 2 a lens field isset up adjacent to the field electrodes 1 and 3 which diverts the red(R), blue (B) and green (G) electron beams from the straight angularpaths which they follow in traversing the space between the beam sourceand the first field electrode 1, into the bent or curvilinear paths,which terminate respectively on the red (r) blue (17) and green (g)phosphor lines on the line screen 5'. Since light rays would passstraight through the apertures in the grills 1 and 3 and impinge uponareas other than the ones (r, b and g) upon which the focused electronbeams (R, B and G) impinge, it will be apparent why the method of theearlier filed Law disclosure and the method of French Patent 866,065cannot be used in laying out the pattern of a screen for use in acathode-ray tube of the lenticular grill variety.

In plotting the distribution of the color areas to be applied to thescreen of the kinescope it is not necessary to expose the photographicplate 7 to the action of all three of the guns 29R, 29B, 296. Excellentresults have been achieved by employing a stencil made by exposing asingle electron-sensitive plate to the scanning action of a single gun.In this case, using a 9 x 12" (108 square inches) plate of the abovespecified formula, the exposure time, to a beamof 200 microamperes froma single gun (in this case the blue gun, 29B), was approximately forty(40) seconds. The plate was developed in a Kodalith developer in aperiod of two minutes. When fixed and dried the plate was contactprinted on a standard Kodalith film for examination and retouching, whenrequired. The film was then contact printed to restore the polarity ofthe pattern, as required in-making a silk-screen stencil. The stencilwas made in the usual way, i. e. by using the last mentioned print as anegative to expose the silk-screen gelatin.

In using a stencil made from such a single exposure the diierentcolor-phosphors were laid down on the surface of the screen by shiftingthe position of the stencil with respect to said surface prior toapplying the second and third phosphors. This is illustrated in Figs. 4,5 and 6 wherein 55 represents a silk screen which will be understood toincorporate a stencil having a pattern of apertures corresponding to thepattern photographically recorded on t e plate 7 by the beam from asingle one of the three electron-guns 29 in the plotting apparatus ofFig. 1. Here the silk screen 55 and the glass foundation plate 57, towhich the different color phosphors are to be applied, are provided withpaired holes through which eccentric pins 59 and 61 extend. Beforeapplying the phosphor of the first color, the silk-screen 55 is swung,say, to the left on the pins 59 and 61, as shown in Fig. 4. With thesilkscreen 55 thus positioned on the glass plate 57 a colorphosphor inthe form of a paste is forced through the porous areas of the silkscreen, as with a roller or squeegee, not shown. Thereafter, as shown inFig. 5, the silk screen 55 is swung 180 to the right, on the pins 59 and61 and the second group of color-phosphor lines are applied to the glassplate 57 through the silk-screen, as before. Before applying the thirdgroup of color-phosphor lines, the silk-screen is swung 90, in eitherdirection, from its previous position on the plate 57, as shown in Fig.6. The silk screen should, of course, be thoroughly 6 cleansed beforeusing it in laying down the different colorphosphors.

Where the ultimate in accuracy is required, three photographic platesmay be employed, exposed one at a time, each to the action of adifferent gun. The three silkscreens made from the three separatelyexposed photographic plates may be used, with appropriate centeringmeans, in laying down the separate color-phosphors in any desiredsequence on the foundation plate 57.

After all three of the color-phosphors have been laid down on thefoundation plate 57 it is baked to remove the binder in the phosphorpaste (or ink). Thereafter, the target surface of the screen may bemetalized in the usual way to render it conductive and highly lightreflecting. It is then mounted in place in the target assembly prior toinserting the assembly in the envelope of the cathoderay tube in whichit is to be used.

From the foregoing description it will now be apparent that the presentinvention provides a highly accurate method of and means for recordingthe pattern of impact of electrons upon a target, and one which lendsitself readily for use in plotting the patterns of color-television andstereoscopic-television screens of various mosaic" varieties.

What is claimed is:

5. Method of recording the pattern traced by a moving beam of electronsupon the target of a cathode-ray tube; said method comprising:thermionically generating a beam of electrons with incident generationof light, in an evacuated envelope, mounting an electron-sensitivephotographic surface in said envelope in the same relative position asthe target of said cathode-ray tube, and shielding saidelectron-sensitive photographic surface from lightrays of the visiblerange emitted as an incident to the thermionic generation of said beamof electrons while causing said thermionically generated beam ofelectrons to trace a pattern on said electron-sensitive photographicsurface corresponding to the pattern traced upon said target by the beamin said cathode-ray tube.

2. In the art of manufacturing cathode-ray tubes of the kind containinga screen-unit comprising at least one foraminous electrode having amultiplicity of systematically arran ed apertures therein through whichbeamelectrons pass along diiferent angularly related paths in theirtransit to sub-elemental areas of respectively difierent responsecharacteristics on the mosaic surface of a nearby screen electrode, themethod of plotting the desired relative location on said mosaic surfaceof all subclernetal screen areas of a particular responsecharacteristic; said method comprising: mounting an electrode containingthe same pattern of apertures as said foraminous electrode and aneiectron-sensitive photographic surface in an evacuable envelope in thesame relative position that said forarninous electrode and saidmosaic-surface are to occupy in said cathode-ray tube, evacuating saidenvelope, establishing adjacent to said apertured electrode an electricfield corresponding to the field normally present adjacent to saidforaminous electrode in said cathoderay tube, thermionically generatinga beam of electrons with incident generation of light, within saidevacuated envelope and projecting said beam upon said aperturedelectrode and said electric field along the same angular paths that theelectrons are to follow in their transit to said particularsub-elemental areas in said cathode-ray tube, and photographicallyrecording, as the desired plot, the pattern of impact of said electronsupon said electronsens'itive photographic surface while shielding saidplate from light rays emitted as an incident to the thermionicgeneration of said electrons.

3. In the art of manufacturing cathode-ray tubes of the kind containinga screen-unit comprising at least one foraminous electrode having amultiplicity of systematically arranged apertures therein through whichbeamelectrons pass along different angularly related paths in theirtransit to sub-elemental areas of respectively difier- 7 7 cut responsecharacteristics on the mosaic surface of a nearby screen-electrode, themethod of plotting the desired relative location on said mosaic surfaceof all sub-elemental screen areas of a particular responsecharacteristic; said method comprising: mounting an electrode containingthe same pattern of apertures as said foraminous electrode and anelectron-sensitive photographic surface in an evacuable envelope in thesame relative position that said foraminous electrode and saidmosaic-surface are to occupy in said cathode-ray tube, evacuating saidenvelope, establishing adjacent to said apertured electrode an electricfield corresponding to the field normally present adjacent to theforaminous-electrode in said cathode-ray tube, projecting a beam ofelectrons upon said apertured electrode and upon said electron-lensfield along the same angular paths that the electrons are to follow intheir transit to said particular sub-elemental areas in said cathode-raytube, and photographically recording upon said electron-sensitivephotographic surface, as the desired plot, the pattern of impact of saidelectrons upon said surface subsequent to their passage through saidapertured electrode and said electron-lens field.

4. Method of plotting the desired relative location of the individualareas that are to comprise the mosaic target-surface of a cathode-raytube of the type wherein the cathode-rays pass through a systematicpattern of apertures in a lenticular field electrode and subsequentlytraverse curvilinear paths in their transit to selected ones of saidindividual areas; said method comprising: mounting said lenticularfield-electrode and an electron-sensitive photographic surface in anevacuable envelope in the same relative position that said fieldelectrode and said mosaic target-surface are to occupy in saidcathode-ray tube, evacuating said envelope; establishing Within saidevacuated envelope an electron-lens field of a direction adapted to passelectrons to said photographic surface along curvilinear pathscorresponding to the ones to be traversed by said cathode-rays,generating an electron-beam within said evacuated envelope andprojecting said beam upon 'said photographic surface through saidlenticular-field electrode and thence through said electric field, andphotographically recording upon said electron-sensitive photographicsurface, as the desired plot, the pattern of impact of said electronsupon said surface.

5. In the art of manufacturing a cathode-ray tube of the kind containinga screen-unit comprising at least one lenticular field-electrode havinga multiplicity of systematically arranged apertures therein throughwhich beam-electrons pass along different angularly related paths intheir transit to sub-elemental areas of respectively different responsecharacteristics on the mosaic surface of a nearby screen-electrode, themethod of plotting the desired relative location on said mosaic surfaceof all subelemental screen area of a particular response characteristic,said method comprising: mounting an electrode containing the samepattern of apertures as said lenticular field-electrode and anelectron-sensitive photographic surface in an evacuable envelope in thesame relative position that said lenticular field-electrode and saidscreenelectrode are to occupy in said cathode-ray tube, evacuating saidenvelope, establish ng in the space between said apertured electrode andsaid photographic surface an electron-lens field corresponding to thefield normally present between said field-electrode and said screenelec-- trode in said cathode-ray tube, projecting a beam of electronsupon said apertured electrode along the particular angular paths thatthe cathode-rays are to follow in their transit to said lenticular fieldelectrode in said cathoderay tube whereby the electrons that passthrough the apercorresponding to the desired location of said particularsub-elemental screen-areas in said cathode-ray tube.

6. In the art of manufacturing color-kinescopes of the kind containing ascreen-unit comprising at least one foraminous electrode having amultiplicity of systematically arranged apertures therein through whichbeamelectrons pass along different angularly related paths in theirtransit to sub-elemental areas of respectively different color-responsecharacteristics on the mosaic surface of a nearby color-screen; themethod of plotting the desired relative location on said mosaic surfaceof all subelemental screen areas of a particular color-responsecharacteristic; said method comprising: mounting said foraminouselectrode and an electron-sensitive photographic surface in an evacuableenvelope in the same relative position that said foraminous electrodeand said color-screen are to occupy in said color-kinescope, evacuatingsaid envelope, establishing in the space between said foraminouselectrode and said photographic surface an electric field of a directionadapted to pass a beam of electrons through said foraminous electrode tosaid photographic surface along the particular angular paths that thebeam is to follow in its transit to said particular sub-elementalcolorareas on the mosaic surface of the color-screen of saidcolor-kinescope, projecting a beam of electrons upon said foraminouselectrode and thence through said electric leld to said photographicsurface, and photographically recording upon said surface, as thedesired plot, the pattern of impact of said electrons upon said surface.

7. Method of manufacturing a color-kinescope of the kind containing ascreen-unit comprising at least one foraminous electrode having amultiplicity of systematically arranged apertures through whichbeam-electrons pass along different angularly related paths in theirtransit to sub-elemental areas of respectively different colorresponsecharacteristics on the mosaic surface of a nearby color-screen; .saidmethod comprising: mounting an electrode containing the same pattern ofapertures as said foraminous electrode and an electron-sensitivephotographic surface in an evacuable envelope in the same relativeposition that said foraminous electrode and said colorscreen are tooccupyin said color-kinescope, evacuating said envelope, establishing inthe space between said apertured electrode and said photographic surfacean electric field of a direction adapted to pass a beam of electronsthrough said apertured electrode to said photographic surface along theparticular paths that the beam is to follow in its transittosub-elemental areas of a particular one of said color-responsecharacteristics on the mosaic surface of the color-screen of saidcolor-kinescope, projecting a beam of electrons upon said aperturedelectrode and thence through said electric field to said photographicsurface whereby photographically to record the pattern of impact of saidelectrons upon said surface, and then applying a color-phosphor of saidparticular color-response characteristic to a screen-plate in thepattern disclosed by said photographic recording.

Somers Sept. 26, 1939 Epstein Aug. 5, 1941

7. METHOD OF MANUFACTURING A COLOR-KINESCOPE OF THE KIND CONTAINING ASCREEN-UNIT COMPRISING AT LEAST ONE FORAMINOUS ELECTRODE HAVING AMULTIPLICITY OF SYSTEMATICALLY ARRANGED APERTURES THROUGH WHICHBEAM-ELECTRONS PASS ALONG DIFFERENT ANGULARLY RELATED PATHS IN THEIRTRANSIT TO SUB-ELEMENTAL AREAS OF RESPECTIVELY DIFFERENT COLORRESPONSECHARACTERISTICS ON THE MOSAIC SURFACE OF A NEARBY COLOR-SCREEN; SAIDMETHOD COMPRISING: MOUNTING AN ELECTRODE CONTAINING THE SAME PATTERN OFAPERTURES AS SAID FORAMINOUS ELECTRODE AND AN ELECTRON-SENSITIVEPHOTOGRAPHIC SURFACE IN AN EVACUABLE ENVELOPE IN THE SAME RELATIVEPOSITION THAT SAID FORAMINOUS ELECTRODE AND SAID COLORSCREEN ARE TOOCCUPY IN SAID COLOR-KINESCOPE, EVACUATING SAID ENVELOPE, ESTABLISHINGIN THE SPACE BETWEEN SAID APERTURED ELECTRODE AND SAID PHOTOGRAPHICSURFACE AN ELECTRIC FIELD OF A DIRECTION ADAPTED TO PASS A BEAM OFELECTRONS THROUGH SAID APERTURED ELECTRODE TO SAID PHOTOGRAPHIC SURFACEALONG THE PARTICULAR PATHS THAT THE BEAM IS TO FOLLOW IN ITS TRANSIT TOSUB-ELEMENTAL AREAS OF A PARTICULAR ONE OF SAID COLOR-RESPONSECHARACTERISTICS ON THE MOSAIC SURFACE OF THE COLOR-SCREEN OF SAIDCOLOR-KINESCOPE, PROJECTING A BEAM OF ELECTRONS UPON SAID APERTUREDELECTRODE AND THENCE THROUGH SAID ELECTRIC FIELD TO SAID PHOTOGRAPHICSURFACE WHEREBY PHOTOGRAPHICALLY TO RECORD THE PATTERN OF IMPACT OF SAIDELECTRONS UPON SAID SURFACE, AND THEN APPLYING A COLOR-PHOSPHOR OF SAIDPARTICULAR COLOR-RESPONSE CHARACTERISTIC TO A SCREEN-PLATE IN THEPATTERN DISCLOSED BY SAID PHOTOGRAPHIC RECORDING.